In certain industries it is extremely important that there be provided a seal for bearings that supports rotating shafts which prevent the lubricants associated with the bearings from leaking externally of an associated housing or bearing support and for preventing foreign particles in the environment which the shaft is being used from working itself through the seal and into the lubricant for the bearing. Such an industry is the food preparation industry in which it is extremely important that the lubricant does not mix with the food particles and in which the food particles do not work themselves into the bearings and lubricants.
It is heretofore been known to provide a metal sealing ring which is fixed to the bearing housing and has internal labyrinth-type grooves therein which tend to scrape lubricants moving axially along the shaft and to thereby prevent lubricants from moving externally of the housing. Conventionally with such a sealing ring there is provided an external cap that is fixed to the housing and has a sealing ring that fits externally of the aforementioned ring and which prevents material from moving internally of the housing through the latter ring. The difficulty with this type of arrangement is that there is no complete seal between the internal and external sides of the housing. The cap with its sealing ring surrounding the shaft while limiting movement of material into the housing nevertheless does permit some material from moving into it. This type of seal is never completely acceptable since the shaft is rotating relative to the seal and eventually the seal wears. This, of course, permits foreign matter to enter into the housing and to eventually damage the bearings. The life of the bearings is extremely long so long as they are properly lubricated and no foreign matter enters into the area. In the food industry, for example, in which large pumps handle the food, such pumps will in many instances operate twenty-four hours a day and continuously from day to day. Because of this, when the bearings do fail the entire line utilizing food products from the pump must be shut down. Also, if for any reason the lubricant for the bearings is permitted to move externally of the housing, the possibility of contaminating the food becomes greater and under normal procedure such a pump will be shut down until a new and suitable seal is provided.